Kusangalatsa kwa ma harmonics achiwiri mu spectrum yotakata
Kuyambira pomwe akatswiri ofufuza adapeza zotsatira za kuwala kwachiwiri m'zaka za m'ma 1960, kwachititsa chidwi chachikulu, ndipo mpaka pano, kutengera mphamvu yachiwiri ya harmonic, komanso mphamvu ya pafupipafupi, yatulutsa kuchokera ku ultraviolet yoopsa kupita ku gulu lakutali la infrared.ma laser, idalimbikitsa kwambiri chitukuko cha laser,kuwalakukonza chidziwitso, kujambula zithunzi za microscope zowoneka bwino kwambiri ndi madera ena. Malinga ndi nonlinearkuwalandi chiphunzitso cha polarization, even-order nonlinear optical effect imagwirizana kwambiri ndi crystal symmetry, ndipo nonlinear coefficient si zero kokha mu non-central inversion symmetric media. Monga second-order nonlinear effect yoyambira kwambiri, ma harmonics achiwiri amalepheretsa kwambiri kupanga kwawo ndi kugwiritsa ntchito bwino mu quartz fiber chifukwa cha mawonekedwe a amorphous ndi symmetry ya center inversion. Pakadali pano, njira za polarization (optical polarization, thermal polarization, electric field polarization) zimatha kuwononga mochita kupanga kusinthasintha kwa material center inversion ya optical fiber, ndikukweza bwino kusagwirizana kwa second-order ya optical fiber. Komabe, njira iyi imafuna ukadaulo wokonzekera wovuta komanso wovuta, ndipo imatha kukwaniritsa mikhalidwe yofananira ya quasi-phase pa mafunde osiyana. Mphete ya optical fiber resonant yochokera pa echo wall mode imachepetsa kukwiya kwa ma harmonics achiwiri. Mwa kuswa kuyanjana kwa kapangidwe ka pamwamba pa ulusi, ma harmonics achiwiri pamwamba pa ulusi wapadera amakulitsidwa mpaka pamlingo winawake, koma amadalirabe pa femtosecond pump pulse yokhala ndi mphamvu yayikulu kwambiri. Chifukwa chake, kupanga zotsatira za kuwala kwachiwiri kosalunjika m'mapangidwe a fiber yonse komanso kusintha kwa magwiridwe antchito, makamaka kupanga ma harmonics achiwiri ozungulira mu kupompa kwa kuwala kosalekeza, ndi mavuto oyambira omwe ayenera kuthetsedwa m'munda wa ma fiber optics ndi zida zosalunjika, ndipo ali ndi tanthauzo lofunikira la sayansi komanso kufunika kogwiritsa ntchito kwambiri.
Gulu lofufuza ku China lapereka lingaliro la njira yolumikizira gallium selenide crystal phase yokhala ndi ulusi wa micro-nano. Pogwiritsa ntchito mwayi wa second-order nonlinearity komanso kulinganiza kwa makristalo a gallium selenide kwapamwamba, njira yosinthira ma second-harmonic ndi multi-frequency imakwaniritsidwa, zomwe zimapangitsa kuti pakhale njira yatsopano yowonjezerera njira zambiri zoyezera mu ulusi ndikukonzekera broadband second-harmonic.magwero a kuwalaKutulutsa bwino kwa mphamvu yachiwiri ya harmonic ndi sum frequency mu scheme kumadalira kwambiri zinthu zitatu zofunika izi: mtunda wautali wolumikizana pakati pa gallium selenide ndiulusi wa micro-nano, kusagwirizana kwapamwamba kwachiwiri komanso dongosolo lalitali la kristalo wa gallium selenide, komanso mikhalidwe yofananira ya gawo la frequency yoyambira ndi frequency doubling mode zakwaniritsidwa.
Mu kuyeseraku, ulusi wa micro-nano wokonzedwa ndi makina ojambulira malawi uli ndi dera la cone lofanana mu dongosolo la millimeter, lomwe limapereka kutalika kwakutali kwa ntchito yosakhala yolunjika kwa kuwala kwa pampu ndi mafunde achiwiri a harmonic. Kutha kwa polarizability kwachiwiri kwa kristalo ya gallium selenide yolumikizidwa kumaposa 170 pm/V, komwe kuli kokwera kwambiri kuposa polarizability yamkati ya nonlinear ya ulusi wowala. Kuphatikiza apo, kapangidwe ka kristalo ya gallium selenide yokonzedwa nthawi yayitali kumatsimikizira kusokoneza kosalekeza kwa ma harmonics achiwiri, zomwe zimapangitsa kuti kutalika kwakukulu kwa ntchito yosakhala yolunjika mu ulusi wa micro-nano kukhale koyenera. Chofunika kwambiri, kufanana kwa gawo pakati pa njira yopopera ya optical base (HE11) ndi njira yachiwiri ya harmonic high order (EH11, HE31) kumadziwika powongolera kukula kwa cone kenako ndikulamulira kufalikira kwa waveguide panthawi yokonzekera ulusi wa micro-nano.
Zinthu zomwe zili pamwambapa zimayala maziko a kusonkhezera bwino komanso kokulirapo kwa ma harmonics achiwiri mu micro-nano fiber. Kuyeseraku kukuwonetsa kuti kutulutsa kwa ma harmonics achiwiri pamlingo wa nanowatt kungapezeke pansi pa 1550 nm picosecond pulse laser pulse pump, ndipo ma harmonics achiwiri amathanso kusangalatsidwa bwino pansi pa pompo ya laser yopitilira ya wavelength yomweyo, ndipo mphamvu yolowera imakhala yotsika ngati ma microwave mazana angapo (Chithunzi 1). Kuphatikiza apo, pamene kuwala kwa pampu kukukulitsidwa ku ma wavelength atatu osiyanasiyana a laser yopitilira (1270/1550/1590 nm), ma harmonics atatu achiwiri (2w1, 2w2, 2w3) ndi ma signal atatu a sum frequency (w1+w2, w1+w3, w2+w3) amawonedwa pa wavelengths iliyonse ya ma frequency conversion wavelength asanu ndi limodzi. Mwa kusintha nyali ya pampu ndi gwero la kuwala lowala kwambiri (SLED) ndi bandwidth ya 79.3 nm, harmonic yachiwiri yozungulira yokhala ndi bandwidth ya 28.3 nm imapangidwa (Chithunzi 2). Kuphatikiza apo, ngati ukadaulo wa chemical vapor deposition ungagwiritsidwe ntchito m'malo mwa ukadaulo wosinthira wouma mu kafukufukuyu, ndipo zigawo zochepa za makristalo a gallium selenide zitha kulimidwa pamwamba pa micro-nano fiber pamtunda wautali, mphamvu yachiwiri yosinthira harmonic ikuyembekezeka kukulitsidwa kwambiri.
CHITHUNZI 1 Dongosolo lachiwiri lopanga harmonic ndipo zotsatira zake zimakhala ndi kapangidwe ka fiber yonse
Chithunzi 2 Kusakaniza kwa mafunde ambiri ndi ma harmonics achiwiri a wide-spectrum pansi pa kupompa kosalekeza kwa kuwala
Nthawi yotumizira: Meyi-20-2024